The present study was undertaken to determine the effect-site concentration of remifentanil for blunting hemodynamic responses to tracheal intubation during total intravenous anesthesia (TIVA) using propofol.

In this prospective, randomized, double-blind study, a total of 126 patients, aged 18-60 (ASA I or II), having undergone elective surgery under TIVA using propofol were investigated. Anesthesia was induced using propofol (target effect-site concentration 4µg/ml) and rocuronium (0.9 mg/kg). Remifentanil was infused at target effect-site concentrations of 0, 2, 4, 6 ng/ml: groups R1, R2, R3 and R4, respectively. The systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and heart rate (HR) were measured pre-induction, and before and after tracheal intubation.

After intubation, the SAP, DAP and HR increased significantly (P < 0.05) in all groups compared to the pre-intubation values. Compared with pre-induction values, the SAP and DAP in groups R1 and R2 increased significantly after intubation (P < 0.05), but those in group R3 remained constant until 1 min after intubation. The SAP and DAP in group 4 however, decreased significantly (P < 0.05) for 3 min after intubation. The HR increased significantly after intubation in groups R1, R2 and R3 compared to the values before intubation (P < 0.05), but that in group R4 being remained constant.

We suggest that the optimal target effect-site concentrations of remifentanil for blunting hemodynamic responses to tracheal intubation were 4 or 6 ng/ml during TIVA using propofol.